The overall project goal is to understand variability in the functional organization of human auditory cortex. We will focus on within-subject variability in cortical auditory event-related responses (evoked, induced) of normal and impaired listeners. Participants are normal-hearing patients with medically intractable epilepsy who have subdural electrodes implanted for clinical purposes. Patients are identified as normal or impaired listeners based on behavioral tests of auditory processing. We hypothesize that patients with normal auditory processing abilities show stimulus-specific effects and low test-retest variability in cortical auditory event-related responses, while patients who are impaired listeners demonstrate reduced stimulus specificity and high test-retest variability. A repeated-measures design will be used to address three specific aims. Intracranial recordings will be obtained using simple and complex auditory stimuli. Preliminary studies have confirmed the feasibility of the methods proposed. Candidate: Dr. Boatman is an audiologist and clinical neurophysiologist with 12 years of clinical research experience using electrophysiological methods to investigate normal and impaired cortical auditory function. The intracranial auditory recording studies proposed complement the candidate's R01-funded electrocortical stimulation mapping research and will provide opportunities for additional training and research mentoring in signal processing and statistical modeling of multi-channel intracranial EEG data. Research: We will address three aims: 1) identify stimulus-related differences in cortical auditory responses; 2) determine test-retest reliability; and 3) quantify within-subject variability by listening ability (normal, impaired). Single channel time-domain and time-frequency analyses will be used, with regression models, to quantify within-subject differences in early and late cortical evoked responses and induced spectral power changes. Multi-channel time-frequency analysis will be used to investigate functional connectivity. Mentoring: Research mentoring activities will include research training for pre-doctoral and post-doctoral trainees from the clinical fields of audiology and neurology (epilepsy, clinical neurophysiology), and cross- disciplinary clinical research training for pre-doctoral students in biostatistics and biomedical engineering.